In xerographic or electrostatographic printing, such as occurs in a copier or "laser printer," an image is created with marking material on a sheet, such as a sheet of paper or a transparency slide. At one point in the electrostatographic printing process, the sheet is typically heated, in a final fusing step, to permanently affix the marking material thereto.
As the sheet passes through the various processing stations in the printing apparatus, a curl or bend is frequently induced therein. This curl or bend may be inherent to the sheet material due to the method of manufacture thereof, or the curl can be induced by the interaction of a sheet with the processing stations within the printer. The curling of the sheet causes problems of handling as the sheet is processed within the printer, frequently producing jams or misfeeds within the printer. Even if the curl is only induced toward the end of the printing process, having curled output sheets is well known as a customer dissatisfier. The problem of sheet curling is particularly evident with relatively small printers or copiers, in which paper passing through the printer or copier must pass through a paper path having relatively tight changes in direction.
The present invention is directed to a decurling apparatus which is, in a preferred embodiment thereof, substantially integral with the fusing apparatus of an electrostatographic printer or copier. The decurling apparatus can be disposed within a replaceable fuser module.